Download Hippocampus reidi (Longsnout Seahorse)

UWI
The Online Guide to the Animals of Trinidad and Tobago
Ecology
Hippocampus reidi (Longsnout Seahorse)
Family: Syngnathidae (Seahorses and Pipefish)
Order: Syngnathiformes (Seahorses, Pipefish and Trumpetfish)
Class: Actinopterygii (Ray-finned Fish)
Fig. 1. Longsnout seahorse, Hippocampus reidi.
[http://www.coralreefphotos.com/longsnout-seahorse-seahorse-facts-caribbean-seahorse, downloaded 26 January 2016]
TRAITS. The longsnout seahorse, also referred to as the slender seahorse (Fig. 1), grows to
approximately 17cm in length (height) and has a narrow body with a long thick snout (Lourie et
al., 2004). Seahorses do not possess pelvic and caudal fins, however they have a propulsive
dorsal fin and use two small pectoral fins to stabilize their bodies and steer while swimming.
There is also a reduced anal fin just below the last trunk ring (Foster and Vincent, 2004). The
coronet is relatively low, but large and convoluted at the top of the head. Rounded low tubercles
UWI
The Online Guide to the Animals of Trinidad and Tobago
Ecology
are typical, with an absence of spines, the lone exception being the eye spines. Males usually
have longer tails than females and possess a brood pouch (Lourie et al., 1999). Both sexes are
usually about the same size (Foster and Vincent, 2004). Coloration usually ranges from yellow to
red, orange, brown and black (Freret-Meurer and Andreata, 2008), profusely spotted with small
brown specks on the body and smaller white spots along the tail. They sometimes exhibit lighter
coloured saddles on the back and sides of the body (Lourie et al., 2004).
DISTRIBUTION. This species has a range in the western Atlantic Ocean from North Carolina
and parts of southern U.S.A., throughout the Caribbean Sea and all the way to Brazil (Lourie et
al., 2004) as shown in red in Fig. 2.
HABITAT AND ACTIVITY. Seahorses are marine animals found primarily in coastal areas
(Foster and Vincent, 2004) and typically live sedentary lives (Vincent and Sadler, 1995) with
small home ranges between 6-20m2 (Rosa et al., 2002). This seahorse uses its muscular,
prehensile tail to anchor itself by wrapping it around suitable objects that can act as a holdfast
(Lourie et al., 1999). The holdfasts used by the longsnout seahorse provide them with shelter
from strong tidal currents, camouflage from predators, and is also used during feeding and
courtship (Dias and Rosa, 2003). These seahorses are frequently found from 15-55m below the
ocean’s surface (Lourie et al., 2004) but can occur at depths of 0.1-75m and are usually
anchored to mangrove roots, sea grass stems, macroalgae, cnidarians, sponges, tunicates,
gorgonians or stone corals (Rosa et al., 2005). This species is active during the daylight hours
from dawn to dusk, and at night it is secured to a holdfast by its tail and will remain there until
dawn (Felício et al., 2006).
FOOD AND FEEDING. Seahorses feed exclusively on live prey and use vision as the primary
tool in their search for food. Hippocampus reidi actively feeds during daylight hours including at
dawn and dusk. The longsnout seahorse is considered an ambush predator that seldomly pursues
prey. Pregnant males commonly have greater frequencies of food consumption than females and
non-pregnant males. Seahorses use suction to catch prey. When in close proximity to prey, it
stretches forward and by expansion of its buccal cavity (mouth) creates a suction force through
its snout, thus sucking the prey up into its mouth (Felício et al., 2006). Common prey of the
longsnout seahorse includes copepods, marine nematodes and carids (Castro et al., 2008).
POPULATION ECOLOGY. Like many seahorse species, longsnout seahorses have been
observed to maintain their own home ranges especially during mating periods. Home ranges of
females are much larger than those occupied by the males. Having small home ranges may have
aided this species in adopting camouflage for their particular environment as well as maintaining
a stable social structure (Foster and Vincent, 2004). Seahorses are usually solitary, but may also
be seen in pairs (Fig. 3), presumably mating partners (Rosa et al., 2007). Older juveniles and
adults have presumably few natural predators as a result of their ability to camouflage
themselves. The presence of bony plates also contributes to them being unappealing to predators
(Lourie et al., 1999). Seahorses are poor swimmers, who prefer anchoring to objects such as
plants, coral or substrates using its prehensile tail and seldom pursue prey in open water
(Kendrick and Hyndes, 2005). Newborn juvenile longsnout seahorses are thought to be
planktonic as experiments in captivity showed them to exhibit phototaxis (moving towards light)
soon after exiting the brood pouch. Mortality due to predation is greatest in young juveniles
UWI
The Online Guide to the Animals of Trinidad and Tobago
Ecology
which are especially vulnerable to piscivorous fish and other planktivorous organisms (Foster
and Vincent, 2004).
REPRODUCTION. This species exhibits monogamy, at least within any given breeding period,
as males would only accept eggs from one given female. Hippocampus reidi also displays low
fecundity with a lengthy periods of parental care (Foster and Vincent, 2004). The mating ritual of
this species lasts for about 25 minutes, and begins with a male and female moving parallel to
each other around a shared holdfast, eventually they hold onto each other’s tails while swirling
around. They would release tails and assume a face-to-face pointing (snouts elevated) position.
The ovipositor of the female is inserted into the male’s brood pouch where the eggs are
deposited. The male and female separate immediately after the eggs have been deposited, and
each individual would grasp a holdfast about 2m apart. The male rocks back and forth for a few
minutes to presumably settle the eggs in his brood pouch (Rosa et al., 2007). The average brood
size of longsnout seahorse is between 1000-1500 eggs (Vincent 1990), and the gestation period
is approximately 2 weeks (Lourie et al., 1999). By the end of the gestation period, males
vigorously force juveniles out of the brood pouch, a process that can last a few hours (Vincent
1990). Newly born individuals are approximately 7mm long (Lourie et al., 1999)
APPLIED ECOLOGY. The IUCN Red List has categorised Hippocampus reidi as data
deficient (IUCN, 2016). It is very popular in the pet industry and as a result it is over harvested
in some areas to fuel the pet trade. The longsnout seahorse is also considered important in folk
medicine and is also often dried and sold as keepsakes. This species is also threatened by shrimp
trawling activities, as they are bycatch in the process (Rosa et al., 2002).
REFERENCES
Castro, A. L. da C., A. de F. Diniz, I. Z. Martins, A. L. Vendel, T. P. R. de Oliveira & I. M. de Lucena Rosa. (2008).
Assessing diet composition of seahorses in the wild using a non-destructive method: Hippocampus reidi
(Teleostei: Syngnathidae) as a study-case. Neotropical Ichthyology (2008) 6(4): 637-644
Dias, Thelma L. P. and I. L. Rosa. (2003). Habitat preferences of a seahorse species, Hippocampus reidi (Teleostei:
Syngnathidae) in Brazil. AQUA Journal of Ichthyology and Aquatic Biology. 6 (4): 165-176
Felício, A. K. C., I. L. Rosa, A. Souto & R. H. A. Freitas. (2006). Feeding behavior of the longsnout seahorse
Hippocampus reidi Ginsburg, 1933. Journal of Ethology (2006) 24:219–225
Foster, S. J. & A. C. J. Vincent. (2004). Life history and ecology of seahorses: implications for conservation and
management. Journal of Fish Biology (2004) 65: 1–61
Freret-Meurer, N.V. & José Vanderli Andreata. (2008). Field Studies of a Brazilian Seahorse Population,
Hippocampus reidi Ginsburg, 1933. Brazilian Archives of Biology and Technology. Vol. 51 n. 4:743 – 751
IUCN Red List. (2016). Hippocampus reidi. http://www.iucnredlist.org/details/10082/0, accessed 27 February 2016.
Kendrick, A. J. & G. A. Hyndes. (2005). Variations in the dietary compositions of morphologically diverse
syngnathid fishes. Environmental Biology of Fishes (2003) 72:415-427.
Lourie, S. A., A. C. J. Vincent & H. Hall. (1999). Seahorses: An Identification Guide to the World’s Species and
their Conservation. Project Seahorse.
Lourie, S.A., S. J. Foster, E. W. T. Cooper & A. C. J. Vincent (2004). A Guide to the Identification of Seahorses.
Project Seahorse and TRAFFIC North America.
Rosa, I. L., Dias, T. L. and Baum, J. K. (2002), Threatened fishes of the world: Hippocampus reidi Ginsburg, 1933
(Syngnathidae). Environmental Biology of Fishes, 64, 378.
Rosa, I. L., R. R. N. Alves, K. M. Bonifácio, J. S. Mourão, F. M. Osório, T. P. R. Oliveira, and M. C. Nottingham.
(2005). Fishers’ knowledge and seahorse conservation in Brazil. Journal of Ethnobiology and
Ethnomedicine 1(12): 1-15.
Rosa, I. L., T. P. R. Oliveira, A. L. C. Castro, L. E. de Souza Moraes, J. H. A. Xavier, M. C. Nottingham, T. L. P.
Dias, L. V. Bruto-Costa, M. E. Araújo, A. B. Birolo, A. C. G. Mai & C. Monteiro-Neto. (2007). Population
UWI
The Online Guide to the Animals of Trinidad and Tobago
Ecology
characteristics, space use and habitat associations of the seahorse Hippocampus reidi (Teleostei:
Syngnathidae).Neotropical Ichthyology (2007) 5(3):405-414
Vincent, A. C. J. (1990). Reproductive Ecology of Seahorses. PhD Thesis, Cambridge University, U.K.
Vincent, A. C. J. and Sadler, L. M. (1995), Faithful pair bonds in wild seahorses, Hippocampus whitei. Animal
Behavior (1995) 50: 1557 – 1569.
Author: Randy Dabie
Posted online: 2016
Fig. 2. Geographic distribution of Hippocampus reidi.
[https://www.flmnh.ufl.edu/fish/discover/species-profiles/hippocampus-reidi/, downloaded 26 January 2016]
UWI
The Online Guide to the Animals of Trinidad and Tobago
Fig. 3. Male and female Hippocampus reidi.
[http://www.realmonstrosities.com/2013/05/seahorse.html, downloaded 3 March 2016]
For educational use only - copyright of images remains with original source
Ecology